Flowgate 10515, an OTDF flowgate, consists of the following elements:

Transcription

1 MAIN Report for NERC Initial Investigation NERC TLR Level 5A Flowgate Kewaunee 345/138 kv Transformer for the loss of Point Beach-North Appleton 345kV Line October 15 17, 2001 Submitted January 14, 2002 This report is submitted in accordance with the NERC Transmission Loading Relief (TLR) Investigation Procedure for the TLR event that occurred on Flowgate from October 15 through 17, The NERC TLR Log is attached. Flowgate is an American Transmission Company (ATCo) flowgate. The TLR Level 5A resulted in the curtailment of firm transmission service. ATCo protected all firm transmission service sinking in ATCo using redispatch of generating units in Wisconsin. Tagged firm transactions not sinking in the ATCo system were adjusted as prescribed through IDC calculations. 1. Description of purpose/cause of hold/curtailment Flowgate 10515, an OTDF flowgate, consists of the following elements: Monitored facility: Kewaunee 345/138 kv transformer (382 MW rating) Contingent facility: Point Beach North Appleton 345 kv Line. The Kewaunee-North Appleton 345kV Line was out of service from 0802 CDT on October 15 to 1815 CDT on October 17 when the Kewaunee Nuclear Unit was also schedule out from September 23 at 2353 CDT and is scheduled back December 2. With the Kewaunee- N.Appleton 345kV Line out, the Point Beach-N.Appleton 345kV Line increases in importance as a critical contingency for the Kewaunee Transformer flows. With the outage of Point Beach-N.Appleton 345kV lines, additional Point Beach Nuclear Unit generation outlet flows towards Kewaunee, thus increasing the Kewaunee Transformer 345 to 138kV flow. In addition, the Kewaunee Transformer and multiple transformers at the North Appleton Substation support the 138kV system in the area around Green Bay. With the Kewaunee-N.Appleton out and the possible trip of Point Beach-N.Appleton, the beneficial post contingency flows through the North Appleton transformers are reduced. Because line flows were increased by scheduled outages, the limiting condition was not part of the permanent set of flowgates. For this TLR event a temporary flowgate was created, which will likely become a permanent flowgate. When the Kewaunee-North Appleton 345kV Line was returned to service, the post-contingency loading problem was reduced and the TLR was released. 2. Facility/flowgate limitations and flows at the time the TLR was initiated The Kewaunee 345/138 kv Transformer is rated at 382 MW (winter emergency). At the time of the initial TLR Level 5A, flow on the Kewaunee Transformer was 249 MW and the flow on the Point Beach-North Appleton Line was 477 MW. Using an LODF of 37.5%, the post-contingent flow would be 428 MW. ATCo contingency analysis showed that if Line

2 Page 2 F-84 at E Krok 138kV Substation is opened, the post contingent flow is reduced approximately 60 MW. ATCo would open this line in the event of the loss of the contingent element. For relief beyond non-firm transactions, ATCo reduced the relief requested by 60MW. Below is a summary of the system conditions at the time the TLR was implemented. 1. Indian Lake-Manistique-Hiawatha 69 kv tie with MECS control area opened to mitigate south to north flow in Wisconsin (TLR Level 4, Flowgate 3525, Stiles Amberg 138 kv Line for the loss of Morgan Plains 345 kv Line). 2. TLR Level 3A Flowgate 3707 (Lore-Turkey River 161 kv Line for the outage of Wempletown-Paddock 345 kv Line). 3. North Appleton Kewaunee 345 kv circuit scheduled outage. 4. Kewaunee Nuclear Station off line (Scheduled, Pmax=511 MW). 5. Initial TLR Level 3A issued for Flowgate 3611, Kewaunee 345/138 kv Transformer. Flowgate created (Kewaunee 345/138 for the outage of North Appleton to Point Beach 345 kv (ODF=.375)). GSFs for Flowgate were not available through the NERC GSF viewer and were calculated at MAIN and distributed to ATCo. 6. NERC in full alert status. 7. DOE in SECON 2 (second highest status). 8. NRC level 3 (highest alert status). 9. GSFs for this flowgate were calculated at MAIN and distributed to ATCo operations because new flowgates are not initially available through the normal GSF viewer. The one-line diagram below illustrates the Kewaunee area system configuration during this TLR event (Green breakers indicating open status).

3 Page 3 3. TLR Levels, timing and relief requested amounts October 15: ATCo requested TLR Level 3A for the Kewaunee 345/138 kv Transformer for the loss of North Appleton-Point Beach 345 kv Line. Since the flowgate element combination did not exist in the IDC, the new Flowgate was created. At 0849 CDT TLR Level 3A was issued for the Kewaunee Transformer (Flowgate 3611) until Flowgate would be available in the IDC after Flowgate was built for the North Appleton-Point Beach contingency. New flowgates are not always ready at the top of the hour. At 0915 CDT, a preliminary TLR Level 3A was confirmed for Flowgate 10515, and Flowgate 3611 was reduced to TLR Level 0. All non-firm transactions affecting this flowgate had been previously curtailed by flowgate 3707, Lore-Turkey River 161 kv Line for the outage of Wempletown-Paddock 345 kv Line. Eight Priority 6 tags totaling 315 MW were providing 41.5 MW relief on Flowgate The IDC Whole Transaction List (WTL) did not show any firm tags sinking outside ATCo for the HB 1000 CDT. Therefore, at 0945 CDT flowgate was increased to TLR Level 4, as ATCo began to redispatch at Pulliam, West Marinette, and Depere generating stations. At 1230 CDT the HB 1300 CDT Whole Transaction List for Flowgate contained two firm transactions not sinking in the ATCo system and therefore not covered under ATCo redispatch for Network Integrated Service Tariff Transactions. The TLR event was increased from TLR Level 4 to TLR Level 5A for the HB 1300 CDT. For that hour, 5.4 MW of tagged firm transactions and 40 MW of ATC redispatch was prescribed. 5.2 MW of tagged firm relief was sinking in the ATCo system and was disregarded in the IDC because the relief was provided through additional redispatch. The amount of relief requested was sufficient to maintain acceptable flows and remained constant through the day. ATCo maintained this level of dispatch even at periods of lighter loading to reduce cycling of nuclear units. At 2200 CDT the Whole Transaction List contained only firm transactions sinking in the ATCo system. ATCo reduced to TLR Level 4 at 2204 CDT and redispatch reduced from 65 MW of relief to 37 MW of relief. At 2325 CDT ATCo had discontinued redispatch and at 0030 CDT the flowgate was reduced to TLR Level 1. During the TLR Level 5A events, the MAIN Security Coordinator issues the TLR without excluding any of the ATCo sinking firm tags. Once issued, the MAIN security coordinator will DISREGARD the tags sinking in ATCo. This will cause them to show up as pink in the acknowledgement column of the congestion management reports. It should also prevent IDC tagging messages to the CAs and PSEs. MAIN then sends out a copy of the IDC screen to its transmission members and makes the appropriate CA calls. MAIN also calls ATCo to give them the redispatch amount which is the total firm curtailments for ATCo sinking tags and the NNL required redispatch for ATCo control areas. During the first hour of the TLR Level 5A event, MAIN conveyed to the sink CAs (WPS/UPPC) that, except for 2 firm tags not sinking in ATCO, all other firm tags would be covered by ATCo redispatch. There was confusion over the Congestion Management Report, and WPS implemented firm tag curtailments for some of the tags. This was noticed in the following hour. The adjustments were corrected and the practices were discussed with ATCo, WPS and MAPP.

4 Page 4 October 16: TLR Level 4 issued at 0450 CDT. Manistique-Hiawatha 69 kv tie was opened and 1 nonfirm transaction curtailed. At 0630 CDT Flowgate Whole Transaction list again contained firm tags not sinking in ATCo and TLR Level 5A was issued with 63 MW of firm relief, of which 62.8 MW of relief achieved through redispatch. At 0930 CDT, ATCo was requested to reduce redispatch from 63 MW to 33 MW. At 1030 CDT ATCo had reduced redispatch to 48.6 MW. This level of redispatch was held constant until 2230 CDT, when TLR Level 4 was issued and redispatch ceased at 2300 CDT. Manistique- Hiawatha 69 kv Circuit remained opened and the TLR was reduced to level 1 at 2330 CDT. October 17: TLR Level 4 issued at 0625 CDT and increased to TLR Level 5A at the bottom of the hour. About 62.5 MW relief was achieved through ATCo redispatch and.2 MW from curtailed firm tags. Requested relief did not change through the day. At 1820 CDT, Line R-304 (North Appleton Kewaunee 345 kv) returned to service and the TLR event was released to zero. 4. Transmission and generation outages or changes from prediction that may have contributed 1. Indian Lake-Manistique-Hiawatha 69 kv Tie with MECS control area opened to mitigate south to north flow in Wisconsin (TLR Level 4, Flowgate 3525, Stiles Amberg 138 kv for the loss of Morgan Plains 345 kv). 2. North Appleton Kewaunee 345 kv Circuit scheduled outage. 3. Kewaunee Nuclear Station scheduled off line. 5. Procedures implemented prior to hold/curtailment During the periods in which all firm transactions in the Whole Transaction List for Flowgate were sinking in the ATCo system, the TLR was reduced to Level 4, curtailing all non-firm transactional flow and redispatching as necessary. GSFs for this flowgate were calculated at MAIN and distributed to ATCo operations because new flowgates are not initially available through the normal GSF viewer. ATCo investigations of potential operating options determined that opening of Line F-84 (Kewaunee-E.Krok 138kV) would reduce the post-contingency loading on the Kewaunee Transformer. Analysis showed that it would reduce the post-contingent flow by 60 MW. ATCo would take the action in the event of the loss of the contingent element. For relief beyond non-firm transactions, ATCo took this operational option into account when requesting relief.

5 Page 5 6. Compare Complete Transaction Curtailment List with the Whole Transaction List as generated by the IDC, before and after curtailments Below is a sample Whole Transaction List from October 15 for hour beginning 1000 CDT. It is typical for the on-peak hours during this TLR. The second transaction list is taken from the Congestion Management Report for the TLR Level 5A reissue for hour beginning 1500 CDT on October 15. In this instance, the 6.7 MW relief required from the firm tags sinking in ATCo was achieved through redispatch, and.2 MW relief was obtained through the curtailment of firm transactions passing through ATCo.

6 Page 6 7. Known Transactions not in the IDC and actions taken There were no known transactions not listed in the IDC Whole Transaction List. 8. SCIS or other system messages SCIS message for October 15, 2001 to October 18, 2001 that may be considered relevant to the TLR Level Level 5. MAIN (for Alliant) 10/17/2001 7:56:00 AM Critical Infrastructure Protection Stage 1 Report Reported by MAIN (for Alliant) Lou Leffler 10/15/2001 9:57:00 AM Security Alert update Lou Leffler 10/15/ :56:00 PM SCIS Cutover-Please note MAIN Time Stamp (CST) 10/16/2001 9:17:00 AM MAIN called the IDC help desk. Subject IDC reboot They stated they are doing a quick reboot. Sender OATI Time Stamp (CST) 10/16/2001 9:26:00 AM Subject IDC up again imo 10/16/ :37:00 AM ISO-NE Time Stamp (CST) 10/16/2001 6:25 PM It should be up again soon. The IDC system is available again, Thank you for your patience, IDC Helpdesk NYISO evacuating to backup control center - due to failure of redundant UPS SUSPICIOUS PLANT ACTIVITY David Souder Time Stamp (CST) 10/17/2001 4:06:00 AM Subject System Frequency MAIN security desk Time Stamp (CST) 10/17/2001 5:03:00 AM Subject Called help desk about IDC alarms Last 2 mornings system frequency has dipped to Hz across the 06:00 ramp. Can anyone provide information? MAIN called the IDC help desk about the IDC alarms. They appear to be about 20 minutes late. Sometimes they don't have an audible. They will investigate.

7 Page 7 Lou Leffler Time Stamp (CST) 10/17/2001 6:26:00 AM Subject SCIS note Main scop Time Stamp (CST) 10/18/2001 8:41:00 AM Subject new SCIS??? Tom Campbell Time Stamp (CST) 10/18/2001 9:00:00 AM Subject Free Form Messages are now posting properly Lynn Constantine Time Stamp (CST) 10/18/ :00:00 AM Subject SCIS We will be moving to the secure SCIS server today.. the new SCIS alarms, but does not show new messages. I also show 10 TLR messages, but the amount can't be cleared. Please investigate. Message that were posted earlier are list (we deleted most of the test messages though). SCIS experienced problems this morning, but we believe they have been rectified. We just completed testing -- posting test messages and then deleting them. All appears to be working as expected. If you continue to experience any difficulties, please me at support@nerc.com. Lynn Costantini 9. State estimator snapshots and security analysis including and contingency analysis or stability analysis along with any other recorded data indicating the need for TLR Not Available 10. ATC Limitations before, during, and after the event The implementation of TLR Level 3A or higher resulted in the posting of 0 MW ATC for hourly and daily transmission service for directions relating to WPS, MGE, DPC, and UPPC imports. MAIN restricts ATC for paths with TDFs greater than or equal to 3% on monitored facilities determined to be constraining in the ATC calculations. The hourly and daily ATCs for imports into WUMS were 0 MW from the day before and same day ATC calculations. These directions were limited by the Kewaunee Transformer and were calculated to be 0 MW for all day ahead and same day studies for the period of October 15 through 17, the duration of the TLR event. With the North Appleton-Kewaunee 345 kv circuit in service, WPS, UPPC, and MGE had a positive ATC value for directions previously affected by Flowgate The CE-DPC direction remained 0, but was limited by ALTW line Savanna York 161 kv. 11. Actions taken to avoid future hold/curtailments The transmission outage was coordinated with the outage of the Kewaunee Plant outage to minimize the effect on the transmission system. ATC values were reduced during the outage and will be for future outages.

8 Page Re-dispatch actions taken Below is a table which details hourly redispatch actions taken by generating unit.

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12 Page If Firm transaction curtailment took place, description of Transactional Contribution Factor calculation and results as well as how necessary relief was obtained through network service and native load contribution Below is a sample Congestion Management Report with the curtailments of network service and native load contributions during this TLR. ATCo fulfilled all firm curtailment obligations through redispatch. Tagged firm transactions sinking in the ATCo system were disregarded in the Interchange Distribution Calculator and the ATCo operator was alerted to the additional relief required through redispatch. The Congestion Management Report below was generated for hour beginning 1700 on October 16. A typical TLR Level 5A issue for this event would have the approximate ratios: 86.2% 41.8 MW (NNL responsibility for a ATCO CAs, provided by ATCo redispatch) 13.4% 6.5 MW (firm tags sinking in ATCO, covered by ATCO redispatch) 0.4 % 0.2 MW (curtailed firm tags not covered by ATCo redispatch) 14. Other options considered before/during to avoid hold/curtailment ATCo studies show that if they open line F-84 at E Krok 138, it will bring the post-contingent flow down approximately 60 MW. This action would be implemented upon the loss of the contingent element.

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